US20180241199A1 - Power distribution systems and methods of performing zone selective interlocking in power distribution systems with a communication network - Google Patents

Abstract

A circuit protection device for an electrical distribution system includes a trip unit, a network interface, a processor, and a memory device. The trip unit is configured to selectively trip to prevent a flow of electrical current through the circuit protection device. The network interface is configured for communicative coupling to a communication network. The memory device stories instructions that, when executed by the processor, cause the processor to transmit, using the network interface, zones selective interlocking (ZSI) data to another circuit protection device coupled to the communication network. The ZSI data is formatted according to a network communication protocol of the communication network.

Description

BACKGROUND
• The present application relates generally to power distribution systems and, more particularly, to methods of operating power distribution systems including a communication network.
• Known power distribution systems include a plurality of switchgear lineups including circuit breakers that are each coupled to one or more loads. The circuit breakers typically include a trip unit that controls the circuit breakers based upon sensed current flowing through the circuit breakers. More specifically, the trip unit causes current flowing through the circuit breaker to be interrupted if the current is outside of acceptable conditions.
• Some known circuit breakers are programmed with one or more current thresholds (also known as “pickup” thresholds) that identify undesired current levels for the circuit breaker. If a fault draws current in excess of one or more current thresholds for a predetermined amount of time, for example, the trip unit typically activates the associated circuit breaker to stop current from flowing through the circuit breaker. However, in power distribution systems that include a plurality of circuit breakers, a typical arrangement uses a hierarchy of circuit breakers. Large circuit breakers (i.e., circuit breakers with a high current rating) are positioned closer to a power source than lower current feeder circuit breakers and feed the lower current feeder circuit breakers. Each feeder circuit breaker may feed a plurality of other circuit breakers, which connect to loads or other distribution equipment.
• A fault may occur anywhere in the circuit breaker hierarchy. When a fault occurs, each circuit breaker that has the same fault current flowing through it may detect different amounts of fault current as a result of varying sensor sensitivities and/or tolerances. When the fault occurs, the circuit breaker closest to the fault should operate to stop current from flowing through the circuit breaker. If a circuit breaker higher in the hierarchy trips, multiple circuits or loads may unnecessarily lose service.
• To accommodate for the varying tolerances and to ensure that multiple circuit breakers do not unnecessarily trip based on the same fault current, the current thresholds of at least some known circuit breakers are nested with each other to avoid overlapping fault current thresholds. In some other known systems, circuit breakers in a lower tier send coordination or blocking signals to higher tier circuit breakers upon detection of a fault current and the upper tier circuit breakers' operation is coordinated with the operation of the lower tier circuit breaker in response to the blocking signal. The signals are typically transmitted over a dedicated connection between a blocking signal output in the lower tier circuit breaker and a blocking signal input in each upper tier circuit breaker with which the lower tier circuit breaker must be coordinated. The blocking/coordination signals are typically a simple binary (on/off) signal in which the presence of a voltage indicates a blocking signal and the absence of a voltage indicates the absence of a blocking signal. Some known systems incorporate a third signal, such as a periodic pulse, to add an additional indication, such as to confirm there is no blocking signal but the connection between circuit breakers is still functioning. Such known systems do not provide any additional information from the lower tier circuit breaker to the upper tier circuit breakers in connection with the blocking signal.
• In certain system topologies, circuit breakers known as ties, which connect distribution busses in the same tier of a system with multiple sources supplying multiple busses, cannot detect fault current direction. The trip unit in the tie does not know whether current is flowing through the tie from right to left or left to right. When a fault occurs the tie must send a blocking signal to upper tier devices on all connected sources. This results in the undesirable operation that all source devices are blocked when it may otherwise be desired that at least one of them not be blocked.
• At least some known power distribution systems include circuit protection devices operable in at least two protection modes: a normal protection mode and a maintenance mode. In the normal protection mode, current thresholds (also known as “pickup” thresholds) that identify undesired current levels are set to protect equipment, such as a load or other protection devices. The maintenance mode is commonly activated by a person when the person will be interacting with a load or protection device downstream (in a lower tier) from a protection device. In the maintenance mode, the protection device's settings are adjusted to make it more sensitive to undesired current levels and, if possible, decrease the amount of time needed by the protection device to react to an undesired current level. Thus, a protection device is easier and/or quicker to trip when the maintenance mode is enabled. The maintenance mode of a protection device is typically manually enabled and disabled by a person. Failure of a person to enable a maintenance mode in a protection device in some known systems increases the danger to a person working downstream from the protection. Failure to return the protection device from the maintenance mode to the normal protection mode may increase the likelihood that the protection device will trip unnecessarily.
• At least some known power distribution systems include circuit protection devices with ground fault detection capabilities. A circuit protection device that disconnects a circuit when it detects that electric current is not balanced between conductors, for example between a line conductor and a neutral conductor, may be referred to as a residual current device (RCD). RCDs include, for example, ground fault circuit interrupters (GFCIs), ground fault interrupters (GFIs), appliance leakage current interrupters (ALCIs), residual-current circuit breakers with overload protection (RCBOs), and electronic residual-current circuit breakers with overload protection (eRCBOs). Ground fault detection capabilities of a circuit protection device are often controlled based only on data that is collected directly by the circuit protection device without full knowledge concerning operation of other circuit protection devices or other portions of the power distribution system.
• Some known power systems utilize relatively simple circuit protection devices in connection with a centralized controller. The centralized controller receives data from sensors disposed throughout the power distribution system. The centralized controller commands and coordinates operation of the various circuit protection devices in the power distribution system based on the sensed data.
BRIEF DESCRIPTION
• In one aspect, an electrical power distribution system includes a first circuit protection device coupled to an electrical power source and a second circuit protection disposed downstream of the first circuit protection device. The first circuit protection device includes a first trip unit configured to selectively trip to prevent a flow of electrical current through the first circuit protection device, a first network interface communicatively coupled to a communication network, a first memory device, and a first processor. The second circuit protection device includes a second trip unit, a second network interface, a second processor, and a second memory device. The second trip unit is configured to selectively trip to prevent a flow of electrical current through the second circuit protection device. The second network interface is communicatively coupled to the communication network. The second memory device stores instructions that, when executed by the second processor, cause the second processor to transmit, using the second network interface, zone selective interlocking (ZSI) data to the first circuit protection device. The ZSI data is formatted according to a network communication protocol of the communication network.
• Another aspect is a circuit protection device for an electrical distribution system includes a trip unit, a network interface, a processor, and a memory device. The trip unit is configured to selectively trip to prevent a flow of electrical current through the circuit protection device. The network interface is configured for communicative coupling to a communication network. The memory device stories instructions that, when executed by the processor, cause the processor to transmit, using the network interface, zones selective interlocking (ZSI) data to another circuit protection device coupled to the communication network. The ZSI data is formatted according to a network communication protocol of the communication network.
• In yet another aspect, a method of operating an electrical power distribution system including a plurality of circuit protection devices coupled between an electrical power source and a plurality of electrical loads is described. Each circuit protection device of the plurality of circuit protection devices includes a trip unit, a network interface communicatively coupled to a communication network including the plurality of circuit protection devices, a processor, and a memory device. The method includes receiving, by one of the circuit protection devices of the plurality of circuit protection devices, zones selective interlocking (ZSI) data from at least one downstream circuit protection device of the plurality of circuit protection devices. The ZSI data is formatted according to a network communication protocol of the communication network. An operational mode of the one of the circuit protection devices is selectively changed to a restrained operational mode based, at least in part, on the received ZSI data from the at least one downstream circuit protection device.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic block diagram of an exemplary power distribution system.
• FIG. 2 is a diagram of a wireless communication configuration of the power distribution system shown inFIG. 1.
• FIG. 3 is a diagram of a wired communication configuration of the power distribution system shown inFIG. 1 that also provides wireless access to a user.
• FIG. 4 is a diagram of another wireless communication configuration of the power distribution system shown inFIG. 1.
• FIG. 5 is a diagram of another wireless communication configuration of the power distribution system shown inFIG. 1.
• FIG. 6 is a diagram of another wired communication configuration of the power distribution system shown inFIG. 1 that also provides wireless access to a user.
• FIG. 7 is a diagram of a hybrid communication configuration of the power distribution system shown inFIG. 1 including wired and wireless communication within the power distribution system.
• FIG. 8 is a flow diagram of an example method of operating an electrical power distribution system.
• FIG. 9 is a flow diagram of another example method of operating an electrical power distribution system.
• FIG. 10 is an example configuration of a portion of the power distribution system shown inFIG. 1.
• FIG. 11 is a flow diagram of an example method of coordinated maintenance mode operation of an electrical power distribution system.
• FIG. 12 is a flow diagram of an example method of coordinated ground fault detection operation of an electrical power distribution system.
• FIG. 13 is a data flow diagram of an exemplary power distribution system similar to the electrical power distribution system shown inFIG. 1 for testing the response of the system to various electrical conditions.
• FIG. 14 is a data flow diagram of the power distribution system shown inFIG. 13 during exemplary testing for zone selective interlock (ZSI).
• FIG. 15 is a data flow diagram of the power distribution system shown inFIG. 13 during exemplary testing maintenance modes for circuit protection devices.
DETAILED DESCRIPTION
• In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
• The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
• “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
• Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
• As used herein, the terms “processor” and “computer” and related terms, e.g., “processing device”, “computing device”, and “controller” are not limited to just those integrated circuits referred to in the art as a computer, but broadly refers to a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), and other programmable circuits, and these terms are used interchangeably herein. In the embodiments described herein, memory may include, but is not limited to, a computer-readable medium, such as a random access memory (RAM), and a computer-readable non-volatile medium, such as flash memory. Alternatively, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), and/or a digital versatile disc (DVD) may also be used. Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a mouse and a keyboard. Alternatively, other computer peripherals may also be used that may include, for example, but not be limited to, a scanner. Furthermore, in the exemplary embodiment, additional output channels may include, but not be limited to, an operator interface monitor.
• Further, as used herein, the terms “software” and “firmware” are interchangeable, and include any computer program stored in memory for execution by personal computers, workstations, clients and servers.
• As used herein, the term “non-transitory computer-readable media” is intended to be representative of any tangible computer-based device implemented in any method or technology for short-term and long-term storage of information, such as, computer-readable instructions, data structures, program modules and sub-modules, or other data in any device. Therefore, the methods described herein may be encoded as executable instructions embodied in a tangible, non-transitory, computer readable medium, including, without limitation, a storage device and/or a memory device. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein. Moreover, as used herein, the term “non-transitory computer-readable media” includes all tangible, computer-readable media, including, without limitation, non-transitory computer storage devices, including, without limitation, volatile and nonvolatile media, and removable and non-removable media such as a firmware, physical and virtual storage, CD-ROMs, DVDs, and any other digital source such as a network or the Internet, as well as yet to be developed digital means, with the sole exception being a transitory, propagating signal.
• Exemplary embodiments of power distribution systems and methods of operating power distribution systems are described herein. The exemplary power distribution systems include circuit protection devices organized in a wired and/or wireless communication network. The circuit protection devices are able to transmit circuit protection device data formatted in a communication protocol to each other in over the communication network to provide each circuit protection device with detail about the configuration, operation, and current status of the power distribution system and the circuit protection devices in the system. The shared information allows circuit protection device operation to be coordinated based on more complete information than some known systems.
• FIG. 1 is a schematic block diagram of a portion of an exemplary electricalpower distribution system100 includingsources102 providing power toloads104 viacircuit protection devices106.Electrical power sources102 may include, for example, one or more generators, electrical grids, or other devices that provide electrical current (and resulting electrical power) to loads104. The electrical current may be transmitted toloads104 through distribution busses108.Loads104 may include, but are not limited to only including, machinery, motors, lighting, and/or other electrical and mechanical equipment of a manufacturing or power generation or distribution facility. Although connections between components insystem100 are illustrated with a single line for simplicity, it should be understood thatsystem100 will include multiple electrical connections between components, such as a line connection, a neutral connection, and a ground connection. Moreover, some embodiments are multiphase systems including a separate line connection for each phase of electricity.
• In some embodiments,circuit protection devices106 are housed in one or more switchgear units (not shown inFIG. 1). The switchgear units include racks to whichcircuit protection devices106 are mounted within a cabinet.Circuit protection devices106 that are electrically close to each other may be disposed physically close to each other, such as in the same switchgear unit, or physically distant from each other, such as in separate switchgear units, in separate rooms, etc. Similarly,circuit protection devices106 that are electrically distant from each other may be disposed physically close to each other or physically distant from each other.
• In the illustrated embodiment,circuit protection devices106 are arranged in a hierarchy including afirst tier110 and asecond tier112 to provide different levels of protection and monitoring topower distribution system100. For example, a first circuit protection device114 (sometimes referred to as a source circuit protection device) is arranged infirst tier110 to receive current from a first electrical power source116 and provide current to a first bus118. A second circuit protection device120 (sometimes referred to as a feeder circuit protections device) is arranged in thesecond tier112 downstream of first circuit protection device114 and connected to receive current from first bus118. Second circuit protection device120 provides current to a first load122. As used herein, the term “downstream” refers to a direction fromelectrical power source102 towardsload104. The term “upstream” refers to a direction opposite the downstream direction, for example, fromload104 towardselectrical power source102. WhileFIG. 1 illustratescircuit protection devices106 arranged in twotiers110 and112, it should be recognized that any suitable number ofcircuit protection devices106 may be arranged in any suitable number of tiers to enablepower distribution system100 to function as described herein. For example, it should be recognized that one or more additional tiers and/orcircuit protection devices106 may be disposed betweenelectrical power source102 andfirst tier110 in some embodiments. Additionally or alternatively, one or more additional tiers and/orcircuit protection devices106 may be disposed betweenload104 andsecond tier112circuit protection devices106 in some embodiments.
• Theexample system100 includes three distribution busses108 coupled together by twocircuit protection devices106 referred to as ties. First distribution bus118 is connected to second distribution bus124 by a first tie126 (also referred to as a first tie circuit protection device). A second tie128 (also referred to as a second tie circuit protection device) connects first distribution bus118 to a third distribution bus130. Although three busses are shown inFIG. 1,power system100 may include any suitable number of busses, including more or fewer than three busses. First tie126 and second tie128 are sometimes referred to herein as source circuit protection devices that are connected between a source102 (via distribution bus124 or130) and first distribution bus118.
• In the exemplary embodiment,circuit protection devices106 are circuit breakers. Alternatively,circuit protection devices106 may be any other device that enablespower distribution system100 to function as described herein. In an exemplary embodiment, eachcircuit protection device106 insecond tier112 includes an integrated trip unit. Details of an example integrated trip unit are shown for second circuit protection device120, and are omitted from othercircuit protection devices106 for clarity. Second circuit protection device120 includes atrip unit132 operatively coupled to asensor134 and atrip mechanism136.Trip unit132, in an exemplary embodiment, is an electronic trip unit (ETU) that includes aprocessor138 coupled to amemory140, aninput device142, adisplay device144, and a network interface. In some embodiments,trip unit132 does not includeinput device142 and/ordisplay device144.Trip unit132 may include, or may be considered to be, a computing device. In other embodiments,trip units132 may be any other suitable type of trip unit. In some embodiments, one or more ofcircuit protection devices106 include a different type oftrip unit132 and/or is a different type of circuit protection device than at least one other ofcircuit protection devices106.
• Sensor134, in an exemplary embodiment, is a current sensor, such as a current transformer, a Rogowski coil, a Hall-effect sensor, a fiber optic current sensor, and/or a shunt that measures a current flowing throughtrip mechanism136 and/orcircuit protection device106. Alternatively,sensor134 may include any other sensor that enablespower distribution system100 to function as described herein. Moreover,sensor134 may be integrated in acircuit protection device106 or may be separate from an associatedcircuit protection device106.Different sensors134 may be used for different portions ofsystem100. For example,sensors134 infirst tier110 may be different thansensors134 insecond tier112. Eachsensor134 generates a signal representative of the measured or detected current (hereinafter referred to as “current signal”) flowing through an associatedtrip mechanism136 and/orcircuit protection device106. In addition, eachsensor134 transmits the current signal toprocessor138 associated with, or coupled to,trip mechanism136. Eachprocessor138 is programmed to activatetrip mechanism136 to interrupt a current provided to aload104 or an electrical distribution line or bus108 if the current signal, and/or the current represented by the current signal, exceeds a current threshold. Moreover, in some embodiments,processor138 converts the current signal to the amount (i.e., the magnitude) of electrical current represented by the current signal. Thus,circuit protection devices106 can send communication signals to othercircuit protection devices106 that include the amount of current detected rather than a value of the current signal. The receivingcircuit protection devices106 do not need to know what type of current sensor was used to measure the current, thereby permittingcircuit protection devices106 with different types of current sensors or different models of current sensors to be used in a single system. In other embodiments,circuit protection devices106 send a value of the current signal and the receivingcircuit protection devices106 determine the amount of current represented by the current signal based on received data about the transmitting circuit protection device106 (including the type of current sensor used by the transmitting circuit protection device106).
• In the example embodiment,trip mechanism136 is a circuit breaker. An electric signal is provided totrip mechanism136 to cause the circuit breaker to trip and interrupt the flow of current throughtrip mechanism136. In other embodiments,trip mechanism136 includes, for example, one or more other circuit breaker devices and/or arc containment devices. Exemplary circuit breaker devices include, for example, circuit switches, contact arms, and/or circuit interrupters that interrupt current flowing through the circuit breaker device to aload104 coupled to the circuit breaker device. An exemplary arc containment device includes, for example, a containment assembly, a plurality of electrodes, a plasma gun, and a trigger circuit that causes the plasma gun to emit ablative plasma into a gap between the electrodes in order to divert energy into the containment assembly from an arc or other electrical fault that is detected on the circuit.
• Eachprocessor138 controls the operation of acircuit protection device106 and gathers measured operating condition data, such as data representative of a current measurement (also referred to herein as “current data”), fromsensor134 associated with atrip mechanism136 coupled toprocessor138.Processor138 stores the current data in amemory140 coupled toprocessor138. It should be understood that the term “processor” refers generally to any programmable system including systems and microcontrollers, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), programmable logic circuits, and any other circuit or processor capable of executing the functions described herein. The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the term “processor.” In the example embodiments described herein,processor138 also controls network communication by its circuit protection device. In other embodiments,processor138 handles protection operations and a separate processor (not shown) handles network communication.
• Memory140 stores program code and instructions, executable byprocessor138, to controlcircuit protection device106.Memory140 may include, but is not limited to only include, non-volatile RAM (NVRAM), magnetic RAM (MRAM), ferroelectric RAM (FeRAM), read only memory (ROM), flash memory and/or Electrically Erasable Programmable Read Only Memory (EEPROM). Any other suitable magnetic, optical and/or semiconductor memory, by itself or in combination with other forms of memory, may be included inmemory140.Memory140 may also be, or include, a detachable or removable memory, including, but not limited to, a suitable cartridge, disk, CD ROM, DVD or USB memory.
• Input device142 receives input from, for example, a user.Input device142 may include, for example, a keyboard, a card reader (e.g., a smartcard reader), a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), a gyroscope, an accelerometer, a position detector, a keypad, a communications port, one or more buttons, and/or an audio input interface. A single component, such as a touch screen, may function as bothdisplay device144 andinput device142. Although asingle input device142 is shown, atrip unit132 may include more than oneinput device142 or noinput device142.
• Display device144 visually presents information aboutcircuit protection device106 and/ortrip mechanism136.Display devices144 may include a vacuum fluorescent display (VFD), one or more light-emitting diodes (LEDs), liquid crystal displays (LCDs), cathode ray tubes (CRT), plasma displays, and/or any suitable visual output device capable of visually conveying information to a user. For example,processor138 may activate one or more components ofdisplay device144 to indicate thatcircuit protection device106 and/ortrip mechanism136 is active and/or operating normally, is receiving a blocking signal, is transmitting a blocking signal, that a fault or failure has occurred, and/or any other status oftrip mechanism136 and/orcircuit protection device106. In some embodiments,display device144 presents a graphical user interface (GUI) to a user for interaction between the user andcircuit protection device106. The GUI permits the user, for example, to controlcircuit protection device106, monitor operation/status ofcircuit protection device106, test operation ofcircuit protection device106, and/or modify operational parameters ofcircuit protection device106.
• Network interfaces146 allowscircuit protection devices106 to communicate with each other as well as remote devices and systems as part of a wired or wireless communication network. Wireless network interfaces may include a radio frequency (RF) transceiver, a Bluetooth® adapter, a Wi-Fi transceiver, a ZigBee® transceiver, a near field communication (NFC) transceiver, an infrared (IR) transceiver, and/or any other device and communication protocol for wireless communication. (Bluetooth is a registered trademark of Bluetooth Special Interest Group of Kirkland, Wash.; ZigBee is a registered trademark of the ZigBee Alliance of San Ramon, Calif.) Wired network interfaces may use any suitable wired communication protocol for direct communication including, without limitation, USB, RS232, I2C, SPI, analog, and proprietary I/O protocols. Moreover, in some embodiments, the wired network interfaces include a wired network adapter allowing the computing device to be coupled to a network, such as the Internet, a local area network (LAN), a wide area network (WAN), a mesh network, and/or any other network to communicate with remote devices and systems via the network.Circuit protection devices106 transmit and receive communications over the communication network using messages formatted according to an appropriate network communication protocol. In some embodiments, the network communication protocol is an Ethernet communication protocol or an Institute of Electrical and Electronics Engineers (IEEE) 802.11 based communication protocol.
• By communicatively couplingcircuit protection devices106 together in a communication network,circuit protection devices106 are able to communicate detailed data to each other beyond simple binary commands. Moreover, the communication network allowscircuit protection devices106 to communicate with allcircuit protection devices106 communicatively coupled to the communication network. In various embodiments,circuit protection devices106 are configured to transmit various types of circuit protection device data, such as measured electrical current, operating parameters and settings, intended actions, device identification data, maintenance status, error data, other sensor data, data received from other circuit protection devices, and the like, to the communication network for receipt by the othercircuit protection device106 coupled to the network.Circuit protection devices106 are able to cooperate with each other to provide protection based on more complete data about the overall system than might otherwise be available in a power distribution system without a centralized controller.
• Additionally, circuit protection devices are configured, such as by instructions stored inmemory140 and executed byprocessor138, to be capable of communication with devices outside ofpower distribution system100. Thus, a user may establish communication withcircuit protection devices106 using a remote access device (not shown inFIG. 1), such as a computer, a laptop computer, a tablet computer, a smartphone, a personal digital assistant (PDA), a dedicated power distribution system communication device, or the like. The remote access device can be used for any suitable purpose including, for example, reviewing and/or changing circuit protection device settings, monitoring operation ofcircuit protection devices106, remotely controlling circuit protection device setting, initiating tests of circuit protection devices, and the like.
• In various embodiments, as described in more detail below,circuit protection devices106 are configured into a communication network according to any suitable network communication configuration. The communication network may be a wired network, a wireless network, or a combination of wired and wireless network. In some embodiments,circuit protection devices106 communicate directly with each othercircuit protection device106 or remote access device within range of its communication signals. In some embodiments,circuit protection devices106 communicate directly with one or morecircuit protection devices106 that act as network switches to direct communication betweencircuit protection devices106 and any remote access devices. In some embodiments,circuit protection devices106 are configured as a mesh network, while in some embodiments a network switch or router is included within or without the switchgear units ofpower distribution system100. Two or more of above-described configurations, as well as any other suitable configurations, may be combined inpower distribution system100 in some embodiments.
• FIGS. 2-7 are diagrams of several example communication configurations ofpower distribution system100. InFIGS. 2-7 common reference numbers refer to similar components serving similar functions, unless otherwise noted. In each configuration,power distribution system100 is disposed withinswitchgear unit202 surrounded by an arcflash safety boundary204. Although a single switchgear unit and fourcircuit protection devices106 are illustrated,power distribution system100 may include more or fewercircuit protection devices106 and may be disposed in more than one switchgear unit in various embodiments of each communication configuration. Network communication between circuit protection devices in separate switchgear units may be wired or wireless communication.
• FIG. 2 is a diagram of awireless communication configuration200 ofpower distribution system100. This configuration utilizes a single device as the wireless system's access point. Each circuit protection device'snetwork interface146 is awireless network interface146 connected to anantenna206. A firstcircuit protection device208 is configured to function as an access point for the communication network. In some embodiments, first circuit protection device may also communicatively couple the communication network tocircuit protection devices106 disposed in a separate switchgear unit. In the illustrated embodiment, eachcircuit protection device106 is wirelessly, communicatively coupled to firstcircuit protection device208 through wireless signals209. Eachcircuit protection device106 communicates to other devices coupled to the communication network through firstcircuit protection device208. Auser210 may access the communication network, and accordinglycircuit protection devices106, using a remote communication device, such aslaptop computer212 orsmartphone214.Laptop212 andsmartphone214 are wirelessly, communicatively coupled to the communication network through firstcircuit protection device208.
• FIG. 3 is a diagram of awired communication configuration300 that also provides wireless access touser210. This configuration allows a user device to wirelessly connect to a wired system using a single device, with that device acting as an access point. Each circuit protection device'snetwork interface146 includes awired network interface146.Circuit protection devices106 are connect bynetwork cables302 to anetwork switch304 to form the communication network.Network interface146 of firstcircuit protection device208 also includes awireless network interface146. Although illustrated as asingle network interface146, first circuit protection device may include separate wireless and wired network interfaces146. Firstcircuit protection device208 is configured to function as a network bridge (also referred to sometimes herein as an access point) to facilitate wireless access to the wired communication network. Generally, eachcircuit protection device106 communicates to other devices coupled to the communication network throughnetwork switch304. A secondcircuit protection device306 is indirectly coupled tonetwork switch304 through a thirdcircuit protection device308.User210 may access the communication network, and accordinglycircuit protection devices106, using a remote communication device wirelessly, communicatively coupled to the wired communication network through firstcircuit protection device208.
• FIG. 4 is a diagram of anotherwireless communication configuration400 ofpower distribution system100. This configuration allows the user to connect wirelessly in a peer-to-peer fashion to any chosen device. Each circuit protection device'snetwork interface146 includes awireless network interface146. In this configuration, none ofcircuit protection devices106 functions as an access point. Rather, eachcircuit protection device106 wirelessly communicates directly with the intended communication destination, e.g., a peer-to-peer network. Direct wireless communication is also used for communication betweencircuit protection devices106 andremote communication devices212 and214.
• FIG. 5 is a diagram of awireless communication configuration500 in which awireless access point502 is disposed outside ofswitchgear unit202. This configuration allows the user to connect to the system wirelessly using an external access point device.Circuit protection devices106 andremote communication devices212 and214 are wirelessly, communicatively coupled towireless access point502. Network communication is transmitted wirelessly towireless access point502, which transmits the communication to its intended destination.
• FIG. 6 is a diagram of another wiredcommunication configuration600 that also provides wireless access touser210. Each circuit protection device'snetwork interface146 includes awired network interface146.Circuit protection devices106 are connect bynetwork cables302 tonetwork switch304 to form the communication network. Anaccess point602 is disposed outside ofswitchgear unit202.Access point602 includes awired network interface604 and awireless network interface606.Access point602 is connected to networkswitch304 by anetwork cable302.Wireless network interface606 provides wireless connectivity toremote communication devices212 and214.
• FIG. 7 is a diagram of ahybrid communication configuration700 ofpower distribution system100 including wired and wireless communication withinpower distribution system100. Anaccess point702 is disposed within ofswitchgear unit202.Access point602 includes awired network interface704 for wired connection tocircuit protection devices106 and awireless network interface706 for wired connection tocircuit protection devices708.Access point602 is connected to networkswitch304 by anetwork cable302. The wireless network interface ofaccess point602 provides wireless connectivity toremote communication devices212 and214.
• Theexample communications configurations200,300,400,500,600, and700 may be combined in any suitable combination of wired and wireless connectivity across any number ofcircuit protection devices106 disposed in one ormore switchgear units202.
• FIG. 8 is a flow diagram of anexample method800 of operating an electrical power distribution system, such aspower distribution system100, comprising a plurality of circuit protection devices coupled between an electrical power source and a plurality of electrical loads. Each circuit protection device of the plurality of circuit protection devices include a trip unit, a network interface communicatively coupled to a communication network including the plurality of circuit protection devices, a processor, and a memory.
• At802 one of the circuit protection devices transmits identification data to the other circuit protection devices of the plurality of circuit protection devices over the communication network. The identification data can include information such as a unique identifier of the transmitting circuit protection device, functional capabilities of the transmitting circuit protection device, identification of a load connected to the transmitting circuit protection device, an electrical position (e.g., upstream/downstream) of the transmitting circuit protection device, what type of device that the transmitting circuit protection device is, and/or operational settings of the transmitting circuit protection device. The one of the circuit protection devices receives, at804, identification data from the other circuit protection devices of the plurality of circuit protection devices over the communication network. At806, the one of the circuit protection devices stores the identification data from the other circuit protection devices in its memory. In some embodiments, the receiving circuit protection device determines an approximation of its physical proximity to the other circuit protection and stores the approximation in its memory.
• Connectingcircuit protection devices106 in a communication network insystem100 permits a significant amount of information to be communicated betweencircuit protection devices106. This information enablescircuit protection devices106 to operate based on a more complete picture of the overall operation and conditions ofpower distribution system100. In the example embodiment, for example,circuit protection devices106 are enabled to perform intelligent zone selective interlocking (ZSI) based on data beyond a simple ZSI restraining signal. In some embodiments,circuit protection devices106 do not output a ZSI restraining/blocking signal.
• Generally, circuit protection devices, such ascircuit protection device106, use ZSI to prevent upstreamcircuit protection device106 from tripping due to an excessive current (or other fault condition) when a downstreamcircuit protection device106 has detected the current and should trip to interrupt the electrical current. The ZSI threshold is typically less than the tripping threshold at which the downstreamcircuit protection device106 trips. In response to receiving a blocking signal, the upstreamcircuit protection device106 may shift from an unrestrained mode of operation to a restrained mode of operation, to prevent the upstream and downstreamcircuit protection devices106 from operating at similar trip timing sequences. Additionally or alternatively, the upstreamcircuit protection device106 may switch to operating at, or using, a higher trip threshold, such as switching from a protective threshold to a backup threshold, in response to receiving a blocking signal from a downstreamcircuit protection device106.
• In some embodiments, in an unrestrained mode of operation, an unrestrained trip timing sequence may be executed that includes accumulating time values in which the current exceeds the protective threshold until an unrestrained time threshold is reached. In the restrained mode of operation, a restrained trip timing sequence may be executed that includes accumulating time values in which the current exceeds the backup threshold until a restrained time threshold is reached. If the restrained time threshold or the unrestrained time threshold is reached,circuit protection device106 trips. Alternatively, the unrestrained trip timing sequence and the restrained trip timing sequence may include any other actions or responses that enablecircuit protection devices106 to function as described herein. It should be recognized that the unrestrained trip timing sequence causes a trip signal to be generated in a period of time that is shorter than a period of time in which the restrained trip timing sequence causes a trip signal to be generated.
• The restrained mode of operation may reduce the risk of an upstreamcircuit protection device106 tripping before a downstream circuit protection device during a downstream fault, also referred to as a “nuisance trip”. If the upstreamcircuit protection device106 trips before the downstreamcircuit protection device106, other downstreamcircuit protection devices106 coupled to the upstreamcircuit protection device106 are interrupted and current will not flow to any loads coupled to such downstreamcircuit protection devices106.
• In the example embodiment, when a circuit protection device's monitored electrical current exceeds a ZSI threshold (also referred to sometimes as a “blocking threshold”), thecircuit protection device106 sends ZSI data formatted according to the appropriate communication protocol to othercircuit protection devices106 over the communication network. In some embodiments,circuit protection device106 transmits the ZSI data to all othercircuit protection devices106 insystem100. In other embodiments, eachcircuit protection device106 knows its hierarchical relationship to the othercircuit protection devices106 transmits the ZSI data only to thosecircuit protection devices106 located upstream from the transmittingcircuit protection device106.
• In the example embodiment, the ZSI data includes at least an identification of whichcircuit protection device106 is transmitting the ZSI data and an indication that the transmittingcircuit protection device106 has detected a current exceeding its ZSI threshold. In some embodiments, the ZSI data also includes an amount of electrical current sensed by the transmittingcircuit protection device106. In other embodiments, the ZSI data includes a value of the current signal measured by the transmitting circuit protection device's current sensor, which the receivingcircuit protection device106 converts to an amount of current based on data about the transmittingcircuit protection device106. The ZSI data may also include an indication of the location of the transmittingcircuit protection device106 withinsystem100. For example, the location indication may include a level within the hierarchy ofsystem100, and/or an identification (such as a name, load type, identification number, etc.) of which load104 is served by the transmittingcircuit protection device106. In some embodiments, the ZSI data includes an operational mode in which the transmittingcircuit protection device106 is currently operating. The operational mode may be one of a plurality of operational modes stored inmemory140. Each operational mode will typically include one or more settings, such as pickup thresholds, calibration factors, and the like. Example operational modes include a standard mode, a restrained mode, and a maintenance mode. In some embodiments, the ZSI data includes identification of one or more specific settings currently active in the transmittingcircuit protection device106. ZSI data may also include an intended action to be taken by the transmittingcircuit protection device106. For example, the ZSI data may include an indication that the transmittingcircuit protection device106 intends to trip immediately, intends to trip if the present electrical current remains the same for a specified time, intends to trip according to a particular predefined setting, intends to trip immediately if the electrical current increases above the present value, etc. In some embodiments, the ZSI data includes a percentage of the trip threshold of the transmitting circuit protection device, an expected/predicted time to trip or clear a detected fault, a type of pickup (e.g., a ground fault or a short time), or any other data suitable for use in a zone selective interlocking system.
• In the example embodiment, eachcircuit protection device106 receives operational data (sometimes referred to herein as “additional data”) from all or a portion of the othercircuit protection devices106 insystem100. The additional data can include electrical currents sensed by the othercircuit protection devices106, the present status and operational modes of the othercircuit protection devices106, the location of the other circuit protection devices within the hierarchy ofsystem100, temperature measurements from othercircuit protection devices106, etc. Accordingly, when acircuit protection device106 receives ZSI data from anothercircuit protection device106, the receivingcircuit protection device106 is able to determine how to react to the ZSI data based on the ZSI data, its own operational data (e.g., its sensor data and present operational mode), and additional data received from othercircuit protection device106 rather than slavishly responding to a ZSI blocking signal.
• Thus, for example, if an upstreamcircuit protection device106 receives ZSI data from a downstreamcircuit protection device106, the upstreamcircuit protection device106 may analyze the ZSI data, the current that the upstreamcircuit protection device106 is sensing, the currents sensed by othercircuit protection devices106 as presented in the additional data, and any other relevant additional data to determine whether the potential problem detected by the downstreamcircuit protection device106 is the only problem insystem100 and whether or not the transmitting downstreamcircuit protection device106 is capable of satisfactorily handling the potential problem. If the upstreamcircuit protection device106 determines that the downstreamcircuit protection device106 is able to handle the problem and there are no other problems, the upstreamcircuit protection device106 may switch to a restrained mode of operation. Alternatively, if the upstreamcircuit protection device106 determines that there may be another problem withsystem100, such as by detecting an electrical current larger than should be seen based on the ZSI data and the additional data, the upstreamcircuit protection device106 may decline to switch to the restrained operational mode. Instead, the upstreamcircuit protection device106 may remain in its current operational mode, immediately trip, switch to a more sensitive (e.g., quicker tripping) operational mode, or take any other suitable action. Similarly, if the upstreamcircuit protection device106 receives ZSI data from more than one downstreamcircuit protection device106 within a relatively small period of time, the upstreamcircuit protection device106 may decline to switch to the restrained operational mode and may remain in its current operational mode, immediately trip, switch to a more sensitive operational mode, or take any other suitable action. Moreover, the upstreamcircuit protection device106 may check the relative positions of the two ZSI transmittingcircuit protection devices106 before acting on the ZSI data. If, for example, the two ZSI transmittingcircuit protection devices106 are serving the same load, the upstreamcircuit protection device106 may determine to switch to the restrained operational mode, if it does not detect any other problems withsystem100.
• In some embodiments, thecircuit protection device106 has more options for how to respond to received ZSI data than would typically be found in many known systems. As mentioned above, the receivingcircuit protection device106 may remain in its present operational mode, switch to the restrained mode, immediately trip, or switch to some other operational mode. Additionally, there may be multiple levels of operational modes that are generally categorized under a heading of standard or restrained. For example, acircuit protection device106 may have multiple restrained operational modes, each of which is more restrained than the standard mode, but each of which has somewhat different characteristics from each other restrained mode. Thus, thecircuit protection device106 can provide a response more finely tuned to the particular circumstances and/or the particular conditions ofsystem100 as a whole than would be available if the only options were standard and restrained modes. In embodiments in whichcircuit protection devices106 transmit predicted time to trip or clear a fault as part of the ZSI data, thecircuit protection device106 that receives the ZSI data may adjust how long it remains in a restrained operation mode based the predicted time to trip. Similarly, when the type of pickup is part of the ZSI data, the receivingcircuit protection device106 may determine not to switch to the restrained operation mode if detected fault types do not match.
• After acircuit protection device106 receives ZSI data from anothercircuit protection device106 and determines how to react to the received ZSI data, the receivingcircuit protection device106, in some embodiments, sends a communication to one or more ofcircuit protection devices106. The communication may include its intended action, its present operational mode, the electrical current it is currently sensing, or any other relevant information. Moreover, the receivingcircuit protection device106 may retransmit the ZSI data to othercircuit protection devices106 that may not have received the ZSI data from the original source.
• FIG. 9 is a flow diagram of anexample method900 of operating an electrical power distribution system. The electrical power distribution system includes a plurality of circuit protection devices coupled between an electrical power source and a plurality of electrical loads. Each circuit protection device of the plurality of circuit protection devices comprising a network interface communicatively coupled to a communication network including the plurality of circuit protection devices, a processor, and a memory device. For convenience,method900 will be discussed with reference tosystem100 and the components of system100 (all shown inFIG. 1). It should be understood, however, thatmethod900 may be used with any other suitable electrical power distribution system.
• Themethod900 includes receiving, by a first circuit protection device114 of the plurality ofcircuit protection devices106, zone selective interlocking (ZSI) data from at least a second circuit protection device120 downstream from the first circuit protection device114. The ZSI data is formatted according to a network communication protocol of the communication network.
• At904, first circuit protection device114 determines whether to change an operational mode of the first circuit protection device114 to a restrained operational mode based, at least in part, on the received ZSI data from downstream circuit protection device120.
• In some embodiments, ofcircuit protection devices106 coordinate to provide maintenance mode protection insystem100. Generally, when a maintenance mode operational setting of onecircuit protection device106 is enabled (i.e. its operational mode is switched from its present mode to the maintenance mode), allcircuit protection devices106 that are located physically close to the maintenance mode enabledcircuit protection device106 also switch to a maintenance mode operational setting.
• To accomplish coordinated maintenance mode protection,circuit protection devices106 are configure, such as by instructions stored inmemory140, to determine the physical distance betweencircuit protection devices106. The physical distance represents how closecircuit protection devices106 are physically located to each other, rather than the electrical relationship betweencircuit protection devices106. Whilecircuit protection devices106 that are electrically close may also be physically close, it is not required.Circuit protection devices106 that are electrically distant (or even unrelated) may be housed in a same switchgear unit. Conversely,circuit protection devices106 that are electrically close, such ascircuit protection devices106 fed by a same feedercircuit protection devices106 may be disposed in separate switchgear units.
• In the example embodiment, the physical distance of acircuit protection device106 from another circuit protection device is determined based at least in part on a characteristic of a network communication signal sent by one of the twocircuit protection devices106 and received by the othercircuit protection device106. The characteristic can be any suitable characteristic of the network communication signal for which can be analyzed to determine an approximation of the physical distance that the network communication signal was sent. The approximation of the distance the signal was sent is used as an approximation of the distance between the sending and receivingcircuit protection devices106.
• For example, if a network communication signal is transmitted wirelessly between twocircuit protection devices106, the wireless signal strength of the network communication signal received by a second of thecircuit protection devices106 from a first of thecircuit protection devices106 may be used to determine an approximation of the distance between the first of thecircuit protection devices106 and the second of the circuit protection devices. By comparison of the signal strength of the received network communication signal to the actual or predicted signal strength of the network communication signal when transmitted, the approximate distance between thecircuit protection devices106 may be estimated. The signal strength may be converted to an approximate distance measurement, converted to a percentage, and/or used without conversion. Similarly, in a wired network configuration ofsystem100, the attenuation of the wired network communication signal may be used to determine an approximation of the distance between transmitting and receivingcircuit protection devices106.
• In the example embodiment, the physical locations ofcircuit protection devices106 relative to each other are initially mapped bycircuit protection devices106 whensystem100 is installed. In some embodiments, the physical locations ofcircuit protection devices106 relative to each other are mapped bycircuit protection devices106 periodically (e.g., every time a network communication is received, daily, weekly, monthly, on demand, etc.). In some embodiments the physical locations ofcircuit protection devices106 relative to each other are mapped bycircuit protection devices106 upon occurrence of a triggering event, such as upon receipt of a message indicating a maintenance mode is enabled for acircuit protection device106.
• Eachcircuit protection device106 stores an indication of its approximate distance from each othercircuit protection device106 in itsmemory140. The indication may be a computed distance, a signal attenuation level, one or more groupings ofcircuit protection devices106 by relative degrees of closeness, or any other data suitable for indicating a degree of closeness ofcircuit protection devices106 to each other. For example, allcircuit protection devices106 that are less than a first threshold distance away (or that have a signal strength greater than a threshold value) may be identified in a first group and the remainingcircuit protection devices106 may be identified in a second group. The first group arecircuit protection devices106 that are physically close, while the second group includescircuit protection devices106 that are more distant. Of course, more than two groups and more than one threshold may be used to groupcircuit protection device106.
• When maintenance is to be performed on or in the vicinity of acircuit protection device106, that circuit protection device is typically place in a maintenance mode. In the maintenance mode, the circuit protection device's settings are adjusted to make it more sensitive to undesired current levels and, if possible, decrease the amount of time needed to react to an undesired current level. Thus,circuit protection device106 is easier and/or quicker to trip when the maintenance mode is enabled. In some embodiments, maintenance mode is enabled by a user manually enabling the maintenance mode, such as using a switch, a button, a user interface on or near thecircuit protection device106, or using a remote communication device, such aslaptop computer212 orsmartphone214.
• In other embodiments, maintenance mode is automatically enabled for one or morecircuit protection devices106. Maintenance mode may be automatically enabled based on one or more sensors detecting a human body within a predefined proximity of one ofcircuit protection devices106.
• FIG. 10 is a simplified diagram of aportion1000 ofsystem100 configured for use with manual and/or automatic maintenance mode enablement combined with coordinated maintenance mode protection. In this embodiment,circuit protection devices106 are disposed inswitchgear units1002,1004, and1006 in aroom1007.Sensors1008,1010, and1012 are configured to detect the location of a body relative toswitchgear units1002,1004, and1006.Sensors1008 detect when an operator is accessingcircuit protection devices106 and/or an interior ofswitchgear unit1002,1004, and1006. Thesensors1008,1010, and1012 may be motion detectors, pressure sensors, thermal sensors, door sensors, or any other suitable sensor for detecting when a body may be nearcircuit protection devices106 and/or preparing to accesscircuit protection devices106.Sensor1008 may be, for example, door sensors that detect when doors (not shown) to the interior ofswitchgear units1002,1004, and1006 are opened. Additionally, or alternatively,sensors1008 may be sensor withinswitchgear units1002,1004, and1006 that detect access or movement ofcircuit protection devices106.Sensor1012 detects when a body is enteringroom1007 and may be, for example a door sensor attached to a door (not shown) that provides access toroom1007.Sensor1010 detects when a body is located within anarc flash zone1014.Arc flash zone1014 is defined aroundswitchgear unit1002. For clarity, the arc flash zones that would be defined aroundswitchgear units1004 and1006 are not shown. Generally,arc flash zones1014 are zones in which there may be a risk of injury to a body located in the zone if an arc flash occurred in the switchgear unit that defines the zone. Moreover, in some embodiments, maintenance mode may be automatically enabled for a circuit protection device based on detection of a user's remote communication device in proximity to thatcircuit protection device106. For example, if a user'slaptop computer212 wirelessly connects to acircuit protection device106 using a relatively short-range communication protocol, maintenance mode may be enabled for thatcircuit protection device106. Maintenance mode may, additionally or alternatively, be manually enabled by an operator.
• Whether automatically or manually enabled, when acircuit protection device106, such as a firstcircuit protection device1016, is switched to the maintenance mode, the othercircuit protection devices106 selectively switch to maintenance mode based at least in part on proximity to the maintenance mode enabledcircuit protection device106 and the maintenance status of firstcircuit protection device1016. In some embodiments, the othercircuit protection devices106 detect the maintenance status of first circuit protection device. In other embodiments, the other circuit protection devices receive a maintenance status message from firstcircuit protection device1016 through the communication network. The maintenance status message is transmitted to all circuit protection devices communicatively coupled to the communication network ofsystem100. Alternatively, the maintenance status message may be transmitted to a subset of allcircuit protection devices106. The subset includes only those circuit protection devices that are less than a threshold distance away from firstcircuit protection device1016.
• However the maintenance status of circuit protection device is detected by the othercircuit protection devices106, they determine whether or not to switch to the maintenance mode based in part on their distance from firstcircuit protection device1016. In embodiments in which the maintenance message is transmitted only to the subset ofcircuit protection devices106 that are less than the threshold distance from firstcircuit protection device1016, allcircuit protection devices106 that receive the message know they are close to firstcircuit protection device1016 without any additional analysis being needed. In embodiments in whichcircuit protection devices106 detect the maintenance status of firstcircuit protection device1016 or in which allcircuit protection devices106 receive the maintenance message, eachcircuit protection device106 determines how close it is to firstcircuit protection device1016. More particularly, eachcircuit protection device106 determines if it is less than the threshold distance from firstcircuit protection device1016. The determination may be made based on a characteristic of the maintenance message, a characteristic of previous data messages received from firstcircuit protection device1016, previously provided distance data, data contained in the maintenance message, or based on any other suitable method.
• In the example embodiment, the threshold distance is a distance from firstcircuit protection device1016 to aboundary1018 ofarc flash zone1014. Thus, anycircuit protection device106 withinarc flash zone1014 is also within the threshold distance from firstcircuit protection device1016. InFIG. 10,circuit protection devices106 withinswitchgear units1002 and1004 are withinarc flash zone1014 and less than the threshold distance from firstcircuit protection device1016.Circuit protection devices106 inswitchgear unit1006 are outsidearc flash zone1018 and their distance from firstcircuit protection device1016 equals or exceeds the threshold distance. In other embodiments, the threshold distance may be any other suitable threshold distance. For example, the threshold distance may be based on a size ofroom1007, such that allcircuit protection devices106 withinroom1007 are less than the threshold distance from all other circuit protection devices inroom1007. In such an embodiment,circuit protection devices106 outside ofroom1007 would not be less than the threshold distance fromcircuit protection devices106 withinroom1007.
• Upon determining, by whichever method, that the first circuit protection device's maintenance status includes being switched to maintenance mode, the particularcircuit protection devices106 that are spaced from firstcircuit protection device1016 by less than the threshold distance selectively enable their own maintenance mode. In the example embodiment,circuit protection devices106 that determine they are spaced from firstcircuit protection device1016 by less than the threshold distance will enable their maintenance mode in response to the detection of firstcircuit protection device1016 having its maintenance mode enabled. Becausecircuit protection device106 are communicatively coupled together and receive operational data from multiplecircuit protection devices106, one or more circuit protection device may determine, in some embodiments, not to enable its protection mode due to some other condition insystem100 that takes precedence over switching to the maintenance mode. Similarly, one or more circuit protection device may determine, based on a condition that exists insystem100, to trip in response rather than switching to the maintenance mode.
• Circuit protection devices106 that are further away from firstcircuit protection device1016 than the threshold distance continue to operate according to their present operating mode after determining that firstcircuit protection device1016 has had its maintenance mode enabled. In some embodiments, such distantcircuit protection devices106 may alter their settings to a somewhat more sensitive setting, enable their maintenance operation modes, or take any other suitable protective action based on firstcircuit protection device1016 being in maintenance operation mode and, for example, detection of some other condition insystem100 that indicates extra caution/protection may be desired.
• Moreover, in some embodiments, one or more non-circuit breaker circuit protection devices (not shown) insystem100 may be enabled in response to maintenance mode enablement of firstcircuit protection device1016. For example, an arc flash containment device near firstcircuit protection device1016 may be enabled in response to receiving a maintenance message from firstcircuit protection device1016. Alternatively, another ofcircuit protection devices106 may instruct the arc flash containment device to enable itself when that circuit protection device determines that firstcircuit protection device1016 is operating in the maintenance mode.
• In some embodiments, multiple threshold distances defining multiple zones of proximity to firstcircuit protection device1016 may be used. Different actions may be taken based at least in part on in which zone of proximity to first circuit protection device1016 a particularcircuit protection device106 is located. InFIG. 10, for example, the distance from firstcircuit protection device1016 toboundary1018 may define a first threshold distance, while a distance from firstcircuit protection device1016 to a boundary1020 (e.g., a wall) ofroom1007 may be used as a second threshold distance. The first threshold distance defines the arc flash zone around firstcircuit protection device1016 and the second threshold distance approximately defines an in-room zone around firstcircuit protection device1016. In multiple threshold embodiments,circuit protection devices106 may take different actions based on which zone eachcircuit protection device106 is located within. For example,circuit protection devices106 inswitchgear units1002 and1004 are closer than the first threshold distance (i.e., within arc flash zone1014) and switch to their maintenance mode. The distance betweencircuit protection devices106 inswitchgear unit1006 and firstcircuit protection device1016 is less than the second threshold distance but greater than or equal to the first threshold distance (i.e., they are withinroom1007, but not within arc flash zone1014). Accordingly,circuit protection devices106 inswitchgear unit1006 may switch to an operational mode that is more sensitive/faster than their standard operational setting, but less sensitive/slower than the maintenance mode that is enabled oncircuit protection devices106 inswitchgear units1002 and1004.
• FIG. 11 is a flow diagram of anexample method1100 of coordinating maintenance modes in an electrical power distribution system, such assystem100. The electrical power distribution system, includes a plurality of circuit protection devices. Each circuit protection device includes a network interface communicatively coupled to a communication network including the plurality of circuit protection devices, a processor, and a memory device. The method includes, at1102, transmitting, by each circuit protection device of the plurality of circuit protection devices, a network communication signal to the communication network. The approximate physical distances between the circuit protection devices is determined1104 based at least in part on a characteristic of the network communication signals transmitted by each circuit protection device. A maintenance mode of each circuit protection device of a subset of the circuit protection devices is enabled1106 in response to enablement of a maintenance mode of one circuit protection device of the plurality of circuit protection devices. The subset of the circuit protection devices is determined at least in part by the approximate physical distance of the circuit protection devices from the maintenance mode enabled one circuit protection device.
• In some embodiments, coordinated ground fault detection is provided bysystem100. In such embodiments,circuit protection devices106 share their detected current data with one or more othercircuit protection devices106. Thecircuit protection devices106 that receive the current data are operable, such as by instruction stored inmemory device140, to use the received current data to determine whether or not a ground fault condition exists insystem100.
• FIG. 12 is a flow diagram of anexample method1200 of operating an electrical power distribution system, such assystem100, with coordinated ground fault detection.Method1200 will be described with reference tosystem100 and components ofsystem100. However,method1200 may be used with any suitable electrical power distribution system.
• At1202, eachcircuit protection device106 of a plurality ofcircuit protection devices106 transmits an electrical current communication to a communication network. The electrical current communication includes an indication of an electrical current measured by thecircuit protection device106 using acurrent sensor134. using acurrent sensor134. The electrical current communication is a formatted according to the network protocol of the communication network to whichcircuit protection devices106 are coupled.
• In the example embodiment, eachcircuit protection device106 transmits its electrical current communication to only onecircuit protection device106 that will act as a decision maker, with respect to ground fault detection, forcircuit protection devices106. In other embodiments, eachcircuit protection device106 transmits its electrical current communication to all othercircuit protection devices106 and any or all of thecircuit protection devices106 may perform the further steps ofmethod1200 discussed below.
• The indication of the electrical current included in the electrical current communication is determined by eachcircuit protection device106 from a current signal received from itscurrent sensor134. In some embodiments, eachcircuit protection device106 converts the current signal into an amount of detected current and includes the amount of detected current in the electrical current communication. In other embodiments, the value of the current signal is included in the electrical current communication and the receivingcircuit protection device106 converts the value of the current signal into the amount of detected current.
• To determine whether or not a ground fault condition exists, the electrical current for each circuit protection device should be measured at the same time. In some embodiments, the time for current detection is based on an clock signal within eachcircuit protection device106. In other embodiments, the time is determined based on a synchronization signal. The synchronization signal may be transmitted tocircuit protection devices106 by one ofcircuit protection devices106 or by any other suitable component. In some embodiments, the particularcircuit protection device106 that will act as a decision maker for ground fault detection transmits the synchronization signal. In some embodiments, the particularcircuit protection device106 transmits a request for the electrical current communication to the othercircuit protection devices106. In response to the receipt of the request, each receivingcircuit protection device106 detects its current at the time of receipt, thus allowing the request to function as a synchronization signal.
• At1204, an additionalcircuit protection device106 receives the electrical current communications from the plurality ofcircuit protection devices106. As discussed above, eachcircuit protection device106 may function as the additional circuit protection device or a singlecircuit protection device106 may be designated to function as the additionalcircuit protection device106.
• The additionalcircuit protection device106 determines, at1206 and based on the received electrical current communications, whether a ground fault condition exists in the electrical power distribution system. A ground fault is identified by summing the values of the currents received in the electrical current communications. If the sum of the values is zero, there is no ground fault. If the sum does not equal zero, a ground fault condition exists. In multi-phase systems, the summing may include calculating a vector sum of the current in each electrical phase insystem100. In other embodiments, any suitable method for detecting a ground fault based on current measurements fromcircuit protection devices106 may be used.
• In some embodiments,method1200 includes tripping a trip unit to interrupt electrical current in electricalpower distribution system100 in response to the additionalcircuit protection device106 determining that a ground fault condition exists insystem100. If the additionalcircuit protection device106 is located electrically upstream from the detected ground fault condition, the additionalcircuit protection device106 may trip its own circuit protection device. In some embodiments, the additionalcircuit protection device106 transmits a trip command to anothercircuit protection device106 to cause it to trip its trip unit. The target of the trip command may be predetermined, such as the most upstreamcircuit protection device106 insystem100. In other embodiments, the target of the trip command may be determined at the time of ground fault condition detection. For example, the target of the trip command may be based on the location of the ground fault condition. In such an embodiment, the additionalcircuit protection device106 determines what portion ofsystem100 is affected by the ground fault condition, determines one or morecircuit protection devices106 that protect the determined portion, and transmits a trip command to each of thecircuit protection devices106 that protect the determined portion.
• In at least some embodiments, the power distribution systems described herein are configured to facilitate testing and/or simulation of electrical conditions within the power distribution systems. More specifically, each circuit protection device and/or other component within the power distribution system receives test data representing an electrical condition and generates response data (e.g., circuit protection data) representing a simulated response of the device. As used herein, “simulating” electrical conditions and responses to such conditions refers to the circuit protection devices analyzing the test data associated with the electrical condition using the same or substantially similar process as measured data. However, unlike measured data, the circuit protection devices do not actually change their operational parameters (e.g., trip riming sequence, operational mode, etc.) or cause a trip unit to interrupt current when simulating a response. Rather, the response data indicates what test data the circuit protection device received and the changes that would have been made in response to the test data. The response data is aggregated at a system-level using a communication network to facilitate system-level analysis of the power distribution system for the tested electrical condition. The analysis is repeatable for a plurality of electrical conditions. System-level analysis for a plurality of electrical conditions facilitates reduced testing time in comparison to previous testing systems for power distribution systems. In these testing systems, each circuit protection device is manually and individually tested, which may be a time-consuming process that potentially delays the normal operation of the power distribution system.
• As used herein, an “electrical condition” refers to parameters and instructions that affect the electrical response of the power distribution system. In one example, a fault within the power distribution system is an electric condition. In another example, a maintenance mode for circuit protection devices that adjusts the electrical response of the circuit protection devices is an electrical condition. The electrical condition may be represented as set of predetermined voltage, current, and/or power values. Additionally or alternatively, the electrical condition may be represented as one or more commands or instructions received by the circuit protection devices in the power distribution system. In at least some embodiments, during setup of the electrical power distribution system, the system is tested for a plurality of electrical conditions to ensure the system is configured to operate properly. These tests may be repeated periodically during operation to proactively detect problems developing within the system such that the problems may be addressed prior to the actual electrical condition occurring.
• FIG. 13 is a data flow diagram of an exemplarypower distribution system1300 for testing the response ofsystem1300 to various electrical conditions. In the exemplary embodiment,system1300 is similar to power distribution system100 (shown inFIG. 1), and in the absence of contrary representation,system1300 includes similar components. That is,system1300 includes a plurality ofcircuit protection devices1306 electrically coupled together throughdistribution bus1308. In other embodiments,system1300 includes a different number ofcircuit protection devices1306 in a different configuration (e.g., the configuration shown inFIG. 1).Circuit protection devices1306 are communicatively coupled to each other within acommunication network1350 as described herein. Eachcircuit protection device1306 includes an integrated trip unit1332, asensor1334, and atrip mechanism1336. Trip unit1332 includes aprocessor1338 coupled to amemory1340, aninput device1342, adisplay device1344, and anetwork interface1346. In other embodiments,system1300 and/orcircuit protection device1306 may include additional, fewer, or alternative components, including those described elsewhere herein.
• At least one ofcircuit protection devices1306 is communicatively coupled to aremote access device1352.Remote access device1352 is a computing device that enables a user to monitor data fromcircuit protection device1306. In some embodiments,remote access device1352 is communicatively coupled tocommunication network1350. In other embodiments,remote access device1352 is communicatively coupled to one or morecircuit protection devices1306 using a different communication network.Circuit protection devices1306 are configured to generate, transmit, and receive circuit protection data1354 (also sometimes referred to as “operational data”).Circuit protection data1354 includes one or more parameters, instructions, notifications, and/or other data associated withcircuit protection devices1306.
• Totest system1300 for a particular electrical condition,remote access device1352 is configured to generate atest message1356 and transmittest message1356 to one or morecircuit protection devices1306.Test message1356 includestest data1358 that represents or simulates the electrical condition. That is,test data1358 includes one or more electrical parameters or control signals that simulate the electrical condition. For example, to simulate a fault condition insystem1300,test data1358 includes current data that, when measured bycircuit protection device1306 near the simulated fault condition, would cause trip unit1332 to trip. In at least some embodiments,test message1356 further includes atest identifier1360.Test identifier1360 indicates tocircuit protection devices1306 that testdata1358 is associated with a test or simulation.Test identifier1360 enablescircuit protection devices1306 to differentiate between measured data andtest data1358. In certain embodiments, during standard operation ofsystem1300,circuit protection devices1306 are configured to operate and respond to measured data in parallel to testing responses to electrical conditions, thereby facilitating testing without interrupting operation ofsystem1300. In some embodiments,test message1356 is generated bycircuit protection device1306. For example, in one embodiment,remote access device1352 may transmit aninitial test message1356 tocircuit protection devices1306 for a recurring test such thatsubsequent test messages1356 are generated by at least onecircuit protection device1306.
• Circuit protection devices1306 are configured to respond totest data1358 similar to measured data (e.g., measured current data) fromsystem1300. That is,circuit protection devices1306 receivetest data1358, analyzetest data1358 for any electrical conditions and/or command instructions, and generatecircuit protection data1354 based on the analysis.Circuit protection data1354 includes metadata similar totest identifier1360 that identifiescircuit protection data1354 as associated withtest message1356. In the exemplary embodiment,circuit protection data1354 includes data associated with, for example and not limited to, “measured” electrical parameters, trip responses, operational modes (e.g., maintenance mode), ZSI data, and/or device parameters, such as trip timing sequences.
• However, unlike the measured data,test data1358 does not cause, for example, trip unit1332 to trip orcircuit protection device1306 to switch operating modes (e.g., to a maintenance mode). More specifically,circuit protection device1306 simulates a response to testdata1358 without changing the present operation ofcircuit protection device1306. For example,circuit protection data1354 may include trip data that includes an electric current value, a voltage value, a power value, a trip timing sequence, and/or other data element associated with a simulated trip response of trip unit1332.
• In the exemplary embodiment,circuit protection devices1306 are configured to store a set of testoperational parameters1362. The testoperational parameters1362 represent the operation ofcircuit protection devices1306, and may include measured current data, trip timing sequences, trip thresholds, ZSI thresholds, operational modes, and/or the like. Testoperational parameters1362 do not affect the actual operation ofcircuit protection devices1306, but rather affect the simulated responses ofcircuit protection devices1306 to testdata1358 andcircuit protection data1354. Testoperational parameters1362 may reset for each test performed bysystem1300. Additionally or alternatively, separate testoperational parameters1362 are generated and stored for each test. In certain embodiments, testoperational parameters1362 are defaulted to the actual operating parameters ofcircuit protection devices1306 at the time of the test. In at least some embodiments, at least some test operational parameters are included incircuit protection data1354.
• Circuit protection data1354 is transmitted to othercircuit protection devices1306 and/orremote access device1352. In some embodiments,circuit protection device1306 that generatedcircuit protection data1354 addscircuit protection data1354 to testmessage1356 and transmitstest message1356 to anothercircuit protection device1306. Ifcircuit protection data1354 is transmitted to othercircuit protection devices1306 throughnetwork1350, the othercircuit protection devices1306 are configured to generate additional circuit protection data based at least partially oncircuit protection data1354. For example, as described herein, if a firstcircuit protection device1306 identifies a fault, thefirst protection device1306 includes a ZSI signal incircuit protection data1354 and transmitsdata1354 to an upstreamcircuit protection device1306. The upstreamcircuit protection device1306 detects the ZSI signal and simulates adjusting its trip timing sequence based on the detected ZSI signal.
• In the exemplary embodiment,circuit protection data1354 fromcircuit protection devices1306 is aggregated within asimulation log1364.Simulation log1364 facilitates a system-level analysis ofcircuit protection data1354. In at least some embodiments,simulation log1364 includes a device identifier and timestamp for each response event (e.g., a trip response, a ZSI signal, etc.) to enable timing analysis ofcircuit protection data1354.Simulation log1364 may also includetest data1358 to indicate which electrical condition was tested. In the exemplary embodiment,access device1352 is configured to collectcircuit protection data1354 and generatesimulation log1364 for analysis. In other embodiments,simulation log1364 may be generated bycircuit protection devices1306 ascircuit protection data1354 is generated in response to testmessage1356. In one example,simulation log1364 is transmitted to eachcircuit protection device1306 such thatsimulation log1364 is updated withcircuit protection data1354 at eachcircuit protection device1306.
• Remote access device1352 is configured to facilitate system-level analysis ofcircuit protection data1354 and/orsimulation log1364 to monitor the response ofcircuit protection devices1306 to the tested electrical condition. Unlike some known testing systems that individually test eachcircuit protection device1306,simulation log1364 facilitates analysis of the interaction betweencircuit protection devices1306 and identifying any issues with multiplecircuit protection devices1306 simultaneously. In at least some embodiments,remote access device1352 is configured to displaysimulation log1364 and/orcircuit protection data1354 to a user (not shown) to enable the user to perform the system-level analysis. In certain embodiments,remote access device1352 and/orcircuit protection devices1306 may analyzesimulation log1364 and/orcircuit protection data1354 to detect any potential errors, warnings, or other issues within the data.
• In certain embodiments, at least onecircuit protection device1306 is configured to analyzecircuit protection data1354 and/orsimulation log1364 to generate arecommendation1366.Recommendation1366 indicates an adjustment withinsystem1300, such as adjusting one or more parameters of circuit protection device(s)1306, that may improve the performance of system and/or fixes a potential error in system1300 (e.g., miscalibrated circuit protection devices1306). A user analyzesrecommendation1366 to determine whether or not to apply the recommended adjustment. In some embodiments, if a user approvesrecommendation1366,system1300 automatically applies the recommended adjustment. In one embodiment,circuit protection devices1306 are automatically calibrated withoutrecommendation1366.
• FIG. 14 is a data flow diagram ofpower distribution system1300 shown inFIG. 13 during exemplary testing for ZSI. More specifically,circuit protection devices1306 are tested to determine the trip response and trip timing sequence for eachcircuit protection device1306 during a fault condition.
• With respect toFIGS. 13 and 14, in the exemplary embodiment, when testing ZSI insystem1300,test data1358 includes data representing a fault condition withinsystem1300. More specifically,test data1358 includes data representing a current exceeding a ZSI threshold at one or morecircuit protection devices1306. When a firstcircuit protection device1306 determinestest data1358 includes a “measured” current at the firstcircuit protection device1306 exceeds the ZSI threshold, the firstcircuit protection device1306 transmitstest ZSI data1402 to the othercircuit protection devices1306 throughnetwork1350. In some embodiments, the firstcircuit protection device1306 transmitstest ZSI data1402 to one or more upstream circuit protection devices.Test ZSI data1402 is substantially similar or identical to the ZSI data transmitted bycircuit protection device1306 when the actual measured current exceeds the ZSI threshold.Test ZSI data1402 includes metadata that indicatestest ZSI data1402 is associated withtest data1358 such thatcircuit protection devices1306 that receivetest ZSI data1402 do not change switch operating modes in response. Rather, in some embodiments,circuit protection devices1306 store testoperational parameters1362 associated withtest data1358. In the exemplary embodiment,test ZSI data1402 is included insimulation log1364.
• Circuit protection devices1306 analyze receivedtest ZSI data1402 and determine whether to simulate changing operational modes (e.g., an unrestrained mode to a restrained mode) based at least in part on the analysis. Ifcircuit protection devices1306 simulate changing from a first operational mode to a second operational mode,circuit protection data1354 generated by the changedcircuit protection devices1306 andsimulation log1364 indicate the operational mode change. The changedcircuit protection devices1306 simulate responses to subsequent receivedtest data1358 andcircuit protection data1354 according to the second operational mode. In one example, when a firstcircuit protection device1306 simulates switching to a restrained mode, the firstcircuit protection device1306 simulates a restrained trip timing sequence fortest data1358 representing a measured current at the firstcurrent protection device1306.
• FIG. 15 is a data flow diagram ofpower distribution system1300 shown inFIG. 13 during exemplary testing maintenance modes for circuit protection devices. More specifically,circuit protection devices1306 are tested to simulate a maintenance condition. The maintenance condition represents the physical presence of a maintenance worker or other user proximate to one or morecircuit protection devices1306.
• With respect toFIGS. 13 and 15, in the exemplary embodiment,test message1356 includes amaintenance mode instruction1502.Maintenance mode instruction1502 causes one or morecircuit protection devices1306 to simulate switching to a maintenance mode. That is,circuit protection devices1306 adjust stored test operational parameters without actually switching to the maintenance mode such thatcircuit protection devices1306 analyzes and responds tosubsequent test data1358 based on the adjusted test operational parameters.Circuit protection devices1306 that simulate switching to the maintenance mode transmit a testmaintenance status message1504 to at least a portion ofcircuit protection devices1306. Testmaintenance status message1504 is substantially similar to the maintenance status message generated whencircuit protection device1306 actually switches to the maintenance mode. Testmaintenance status message1504 includes metadata that indicates test maintenance status message is associated withtest message1356. In the exemplary embodiment, testmaintenance status message1504 is included insimulation log1364.
• In response to testmaintenance status message1504,circuit protection devices1306 determine whether or not to simulate switching to the maintenance mode. In the exemplary embodiment, eachcircuit protection device1306 determines a physical distance between a firstcircuit protection device1306 in the maintenance mode and the particularcircuit protection device1306. If the physical distance is within one or more predetermined distance thresholds,circuit protection device1306 may simulate switching to the maintenance mode and transmit a testmaintenance status message1504 to othercircuit protection devices1306. If the physical distance exceeds the distance thresholds,circuit protection devices1306 may continue to operate according to their present operating mode specified in the stored test operational parameters. In some embodiments, rather than determining a physical distance,circuit protection devices1306 identify a zone of proximity associated with testmaintenance status message1504. Ifcircuit protection device1306 is physically within the identified zone,circuit protection device1306 may simulate switching to the maintenance mode.
• Exemplary embodiments of power distribution systems and methods of operating power distribution systems and/or circuit protection devices are described above in detail. The systems and methods are not limited to the specific embodiments described herein but, rather, components of the systems and/or operations of the methods may be utilized independently and separately from other components and/or operations described herein. Further, the described components and/or operations may also be defined in, or used in combination with, other systems, methods, and/or devices, and are not limited to practice with only the power system as described herein.
• The order of execution or performance of the operations in the embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the invention.
• Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
• This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims (19)

What is claimed is:

1. An electrical power distribution system comprising:

a first circuit protection device coupled to an electrical power source, said first circuit protection device comprising:

a first trip unit configured to selectively trip to prevent a flow of electrical current through said first circuit protection device;

a first network interface communicatively coupled to a communication network;

a first memory device; and

a first processor; and

a second circuit protection device disposed downstream of said first circuit protection device, said second circuit protection device comprising:

a second trip unit configured to selectively trip to prevent a flow of electrical current through said second circuit protection device;

a second network interface communicatively coupled to the communication network;

a second processor; and

a second memory device storing instructions that, when executed by said second processor, cause said second processor to transmit, using said second network interface, zone selective interlocking (ZSI) data to said first circuit protection device, the ZSI data formatted according to a network communication protocol of the communication network.

2. An electrical power distribution system in accordance withclaim 1, wherein said second circuit protection device further comprises a current sensor disposed to measure a flow of electrical current through said second circuit protection device, and wherein the ZSI data further comprises an amount of electrical current measured by said current sensor.

3. An electrical power distribution system in accordance withclaim 2, wherein said second memory device further stores operational modes for said second circuit protection device, and wherein the ZSI data further comprises a presently active operational mode of the plurality of operational settings for said second circuit protection device.

4. An electrical power distribution system in accordance withclaim 2, wherein the ZSI data further comprises an intended action to be taken by said second circuit protection device based, at least in part, on the amount of electrical current measured by said current sensor.

5. An electrical power distribution system in accordance withclaim 2, wherein said current sensor is configured to produce a current signal indicative of the amount of electrical current measured by said sensor, and wherein said second memory device stores instructions that, when executed by said second processor, cause said second processor to convert the current signal to the amount of electrical current measured by said sensor.

6. An electrical power distribution system in accordance withclaim 1, wherein said first memory device stores instructions that, when executed by said first processor, cause said first processor to:

receive, using said first network interface, the ZSI data from said second circuit protection device;

determine whether to change an operational mode of said first circuit protection device to a restrained operational mode based, at least in part, on the ZSI data received from said second circuit protection device.

7. An electrical power distribution system in accordance withclaim 6, further comprising a third circuit protection device coupled to the communication network and configured to transmit additional data to said first circuit protection device using the communication network, wherein said first memory device stores instructions that, when executed by said first processor, cause said first processor to:

receive, using said first network interface, the additional data from said third circuit protection device;

determine whether to change the operational mode of said first circuit protection device to the restrained operational mode based, at least in part, on the received ZSI data from said second circuit protection device and the additional data received from said third circuit protection device.

8. An electrical power distribution system in accordance withclaim 1, wherein the communication network comprises a wireless communication network, and said first network interface and said second network interface comprise wireless network interfaces.

9. An electrical power distribution system in accordance withclaim 1, wherein the communication network comprises a wired communication network, and said first network interface and said second network interface comprise wired network interfaces.

10. An electrical power distribution system in accordance withclaim 1, wherein said second circuit protection device does not output a ZSI restraining signal.

11. A circuit protection device for an electrical distribution system, said circuit protection device comprising:

a trip unit configured to selectively trip to prevent a flow of electrical current through said circuit protection device;

a network interface configured for communicative coupling to a communication network;

a processor; and

a memory device storing instructions that, when executed by said processor, cause said processor to transmit, using said network interface, zones selective interlocking (ZSI) data to another circuit protection device coupled to the communication network, the ZSI data formatted according to a network communication protocol of the communication network.

12. A circuit protection device in accordance withclaim 11, wherein said circuit protection device further comprises a current sensor disposed to measure a flow of electrical current through said circuit protection device, and wherein the ZSI data further comprises an amount of electrical current measured by said current sensor.

13. A circuit protection device in accordance withclaim 12, wherein said memory device further stores operational modes for said circuit protection device, and wherein the ZSI data further comprises a presently active operational mode of the plurality of operational modes for said circuit protection device.

14. A circuit protection device in accordance withclaim 12, wherein the ZSI data further comprises an intended action to be taken by said circuit protection device based, at least in part, on the amount of electrical current measured by said current sensor.

15. A circuit protection device in accordance withclaim 11, wherein said memory device stores further instruction that, when executed by said processor, cause said processor to:

receive, using said network interface, downstream ZSI data from a downstream circuit protection device;

determine whether to change an operational mode of said circuit protection device to a restrained operational mode based, at least in part, on the received downstream ZSI data from said downstream circuit protection device.

16. A circuit protection device in accordance withclaim 15, wherein said memory device stores further instruction that, when executed by said processor, cause said processor to:

receive, using said network interface, additional data from an additional downstream circuit protection device;

determine whether to change the operational mode of said circuit protection device to a restrained operational mode based, at least in part, on the downstream ZSI data from said downstream circuit protection device and the additional data from said additional downstream circuit protection device.

17. A method of operating an electrical power distribution system comprising a plurality of circuit protection devices coupled between an electrical power source and a plurality of electrical loads, each circuit protection device of the plurality of circuit protection devices comprising a trip unit, a network interface communicatively coupled to a communication network including the plurality of circuit protection devices, a processor, and a memory device, said method comprising:

receiving, by a first circuit protection device of the plurality of circuit protection devices, zone selective interlocking (ZSI) data from at least a second circuit protection device downstream from the first circuit protection device, the ZSI data formatted according to a network communication protocol of the communication network; and

determining, by the first circuit protection device, whether to change an operational mode of the first circuit protection device to a restrained operational mode based, at least in part, on the received ZSI data from the downstream circuit protection device.

18. A method in accordance withclaim 17, further comprising receiving, by the first circuit protection device, data from all circuit protection devices of the plurality of circuit protection devices that are disposed downstream of the first circuit protection device.

19. A method in accordance withclaim 17, wherein determining, by the first circuit protection device, whether to change the operational mode of the first circuit protection device to a restrained operational mode comprises determining whether to change the operational mode of the first circuit protection device to a restrained operational mode based, at least in part, on the received ZSI data from the downstream circuit protection device and the data received from all circuit protection devices that are disposed downstream of the first circuit protection devices.

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